Armature-winding.



R. E. HELLMUNU.

ARMATURE WINDiNG.

APPLICATION mm: was @1915.

Patented Apr. 1, 1919.

4 I U 2 4w 0 luvsmon I Rude/ff. Hellmund.

ATTORNEY UNITED STATES PATENT ()FFICE.

'EUDOLE E, HELLMUND, OF PITTSBURGH, PENNSYLVANIA, ABSIGN OR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION 03 PENNSYLVANIA.

MATURE-WINDING.

Specification of Letters Patent.

Patented Apr. 1, 1919.

To allwhomitma concern:

Be it known t at I, Ruoocr E. HELL- MUND, a subject of the Emperor of on many, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Armature-windings, of which the following is a specification.

My invention relates to armature windings for dynamo-electric machines, especially of the single-phase commutator type, and it has for its object to provide means whereby the inductive distur ances in coils undergoin commutation shall be minimized, wit 1 consequent improvement of the commutation. p

In the accompanying drawing, Figure 1 is a developed ew of an armature winding as hitherto ene lly constructed, serving to illustrate t e theory of my explanation, Fig. 2 is a similar developed view of an armature windihg embodying my invention; Fig. 3 is a sectionalview showing the flux distribution aboutthe armature conductors and Fi .4 is a. sectional view of a commutator ilust-rating the efl'ects [of sparking caused by improper armature winding.

In single-phase problem of commutation is rendered ex-' tremely difiicult, especially at starting, because of the fact that the field liux alternates and induces a transformer'voltage in the coils which are, for the timefbein short circuited by the brushes. The said transformer voltage causes short ci rcuit currents to flow in said coils and, when gcontact is broken at the brush and the short-circuit current is broken, a harmful spark is produced at the corresponding commutator segment. This spark will increase in intensity with the self-induction of the short-circuited coil. The magnetic flux causing self-induc tion in the short-circuited coils extends from one side of the armature slot to the other and also from the top of a tooth to the stator iron and back to the top of the next tooth, as indicated in Fig. 3. These magnetic fluxes must necessarily die out whenever the short circuit through a coil is broken, and the disappearance of the fluxes induces a voltage in the coil which adds to the short'circuit voltage and increases the intensity of the commutator spark. If it so happens, however, that, when the short-circuit current in a coil in one slot is dying out, an;

commutator motors, the' equal amount of short-circuit current is bemg built up in another coil lying in the same slot, the resultant flux in the first mentioned coil is not changed and, therefore, no volta e of self-induction will be set up' in the circuit which is about to be inter'ru ted. In other words, the commutator spari: will be less'harmful in those cases where the short circuit current, is being transferred from a coil to another coil in the same slots than it.

is in the same case where it is transferred from a certain coil lying in one pair of slots to a coil located in a distinctly separate pair of slots.

By my invention, I so wind an armature that commutation progresses either from one coil to another coil lying in the same slots or from one coil to another coil, half of which lies in the same slot and half of which is in a new slot. The next succeeding coil to be commutateti lies partially in said new slot and, as to theremainder, within still another slot. By this means I provide a gradual transfer from one set of slots to another set,- thus greatly decreasing 'the'rate of change of, the magnetic flux through the short-circuited coils and, in'like degree, re ducing the short-circuit voltage due to selfinduction.

Referring-now to Fig. 1 for a fuller undcrstanding of the principles under] 'ng my invention, I haveshown at 7 .7 t e teeth of a slotted armature of any desired form provided with a commutator 8 having segments 9, 10, 11, 12, 13, 14-, etc. Starting from the commutator segment 9, a conductor 19 passes adjacent to the left-handwall of a slot 15 and thence adiacent to the lefthand wall in a slot 17, returning to the commutator segment 10. Conductors 20 and 21 of the same armature coil also he in the slots 15 and 17 but are not adjacent to the walls thereof. The remaining conductor 22 of the coilin question, however, lies next tothe right-hand wall' in both slots 15 and 17. Passing to the next armature coil, the conductor 23 is in all respects similar to the conductor 19. V

Assumin -that the armature coils move from the right to the left, the transfer of the short-circuit current from the turn 19 to the turn 20 from the turn 20 to the turn 21 and from the turn 21 to the turn 22 will be easy because these turns lie in the same slots and there is therefore no abrupt change in the magnetic flux interlinked therewith. When, however, the brush passes from the commutator segment 12, there is an abrupt transfer of short-circuit current from the turn '22 lying in the slots 15 and 17 to the turn 23 lying in the slots 16 and 18. As will be apparent from an inspection of Fig. 3, there results an abrupt shifting of the short-circuit flux from theslots 15 and 17 to the slots 16 and 18, with consequent pro duction of a high self-induced electrometive force in the turn 22 and burning at the commutator segment 12.

When the-direction ofrotation is reversed, there 7 will be produced, in like manner, a high electromotive forcein the turns-19 and 23 with consequent burning of the -corinnutator segments 10 and '14; The-commutator will therefore assume a condition, as indicated in i 4, wherein c'ertain colnlnutator segments w liCll are conneete to eoils' lying next to the slot-walls are-P Iiicflfaway at the top to a slight degree: g s fafresnlt of this burningorpitting; noi'i'ri' .i'fiintiiet vith the brush is interfered'witll ai tl ftherefore, excessive burningttakes place from normal load current, lowering the upper surface of the segments antquestion to sucha point that successful} operation is impossible.

Turning now to FignQ, illustrating my invention,.l ikeparts are nuin'herei similarly to Fig. 1 for ease of reference. The turn 19, starting from the commutator segment 9, is placedadjacent to the left-hand (will in the slot.,15 and thence adjacent to the right-hand wall in the slot 30 rather than passing through the slot 17 in common with the other members of the same coil. The turns 20, :21 and. 22 are provided with the same pitch as in Fig. 1 so that they lie in the slot 17 hut it will be observed that the turn 20 lies adjacent to the left-hand wall in the slot l7 because of the absence of the turn 19. The turn 23 is given a short pitch similar to that of the turn 19, so that it occupies the right-hand position in 'thc.

slot 17.

Assuming ,the armature to turn from right to left, as in Fig. l,-the transfer from the turn 22 to the; turn 23 will not bees abrupt, as in Fig. 1, because of the fact am, while the left-hand sides of these turnslie in the neighboring slots 15 and 16. tlie'right-i hand portions lie in the same slot 17. v The complete transfer from the-slots l5 and 17 to the slotslti and 18 is notieomplcted until the transfer is made, from the turn to the turn 2-1, a'ehange of similaraabruptriess to that just indicated in connection with turns 22 and 23 because of the fact that right-hand halves of the turns 23 and ill lie in adjacent slots, whereas their left-hand halves lie in the same slot. It will thus be observed that, by doubling the time for shifting the short-circuit current from one pair of slots to another pair of slots, one slot at a time, I am enabled to greatly reduce the sparking at the commutator and, by operating the motor altarnately in each direction, as is common in railway practice. the wear on the commutator will be equalized on all segments thereof.

It will be observed that the turns 19, 23, etc, have a shorter pitch than the remaining; turns and are also of somewhat dill'erent shape. I therefore find it convenient to make these turns from twohalf turns of the appropriate shape, joined at the outer end.

By the use of a compensating winding, practically all sparkpriuluring clcctromo live forces may be cliininatml during normal operation of a motor and, lherei'ore, by the use of my invention for reducing sparking at starting nd by the H51 of a compensating winding to perform the same function during operation, I am. enabled to produce a motor which is practically free from sparkin; under all condilions.

lVhile l have shown my invention in its preferred rmhodimcm".it will be obvious to those skilled in the art that the same result may be achieved by using other types of winding. such. for example, as one in which the pitch of the split turn is greater than that of the remaining turns in each armature coil and I may, if desired, split more than one turn in each coil. All such modifications, howevcr, would differ in operation from that shown only in degree and not in principle and I desire, therefore, that no commutator type, the combination with an armature core member provided with m nvinding slots, of an armature Winding i'nounted in. said slots and comprislng 4m turns, whereby portions of 8 turns lie in each slot, the turns having portions lying in. any one slot forming a windinggroup whereof (3 turns have a pitch of P slots and '2 turns have a pitch of P1 slots, at connect'ion from corresponding portions of each Winding turn to an appropriate segment of the commutator cylinder of said machine, and a brush bearing upon said commutator cylinder of snflicient width to successively short-cirruil each of said winding turns.

3. In a dynanm-clrctric machine of the commutator type. the combination with an urinal nre core member provided with m winding slots of an armature Winding mounted in said slots and comprising 4m turns, whereby portions of 8 turns he in each slot, the turns having portions lying in anyone slot forming a winding group whereof. 6 turns have a pitch of P slots and 2 turns have a itch of P-1 slots, :1 connection from points in said winding spaced apart by 9 turns, where q is, any positive integer to appropriate segments in the commutator cylinder of said machine, and a brush'bearing uponsai'ri commutator cylinder of sufficient Width to successively short-circuit. each of the winding portions determiner] by said points of connection.

4. In a dynmno-electric machine of the commutator type, the combination with an armature core member provided With m winding slots, of an armature Winding mounted in said slots and comprising 4m n turns, where n is any positive integer, where- I v by portions of Sm n turns lie in each slot, the

turns having portions lying in any one slot forming a, winding group whereof 6121. it turns have a pitch of P slots and 2119 it turns have a itch of P +1 slots, a, connection from corresponding portions of each-winding to an appropriate segment of the commutator cylinder of sziid machine, and a brush hear- 

